Oh yes. Heart events work when the heart is at the right color or better. For example, you can see the black heart event at any heart color. You can see the purple heart event if her heart is purple or better, Etc.. It won't matter with the blue heart event if she's at green heart. Just keep trying to trigger it and it'll eventually happen.
Well I was always lucky with events, but I've heard from other people (on this forum) that lots of the events are temperamental in that they are quite stubborn when you try to activate them... All I can suggest is to keep trying really... Good luck!
It took me a couple tries to get this event but it may have been because I didn't have an item slot open. Make sure you've talked to Ellen and Stu at least once. Events won't activate if you haven't talked to all parties involved at least once iirc.